6th Grade Math Textbook, Progress

Addition and Subtraction Expressions

1-10

Word Phrase Expression

sumof 1.2 and 2 1.2
 2

sumof a number and 7 n
 7

5 increased by 20 5 
 20

x increased by 5 x
 5

9 more than 12 12 
 9

10 more thana number c
 10

8 added to6.5 6.5 
 8

a number addedto 4 4 
e

3.2 plusa number 3.2 
b

Word Phrase Expression

differenceof 8 and 0.9 8 0.9

differenceof mand 88 m 88

0.5 decreased by0.1 0.5 0.1

75 decreased by d 75 d

18 less than 30 30  18

2 less thana number s 2

5.5 subtracted from 10 10 5.5

7 subtracted from t t 7

7.2 minusa number 7.2 w

Andie works 4.5 hours on Thursdays and 5.25 hours on Fridays.

To represent the total hours she works on Thursdays and

Fridays, Andie writes a numerical expression:

4.5
5.25

A numerical expression is a mathematical phrase

that has only numbers and operation symbols.

Each of the following is a numerical expression:

60.75 4 
 (147)
 10 32 
 8

Suppose Andie decides to work on Saturdays as well, but does

not know how many hours she will work. She could use a variable

to represent the unknown number of hours worked on Saturdays.

A variable is a symbol used to represent an unknown quantity.

To represent the total hours worked on Thursdays, Fridays, and

Saturdays, Andie writes an algebraic expression:

4.5
5.25
x

An expression that includes a variable is called an

algebraic expression. Here are some examples:

20 a x
5.2 z
 10 w

Study these examples.

1

4

1

2

numerical expression

algebraic expression

Any letter can be used

as a variable.

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